EP1042400A1

EP1042400A1 - Organopolysiloxane materials which can be cross-linked by cleaving alcohols into elastomers

Info

Publication number: EP1042400A1
Application number: EP98948956A
Authority: EP
Inventors: Norman Dorsch; Rudolf Heinrich; Oswin Sommer; Stefan Oberneder; Wolfgang Hechtl
Original assignee: Wacker Chemie AG
Current assignee: Wacker Chemie AG
Priority date: 1997-12-22
Filing date: 1998-09-10
Publication date: 2000-10-11
Anticipated expiration: 2018-09-10
Also published as: KR100347296B1; CA2316175C; KR20010033444A; CA2316175A1; RU2189995C2; PL341311A1; ATE210700T1; WO1999032551A1; DK1042400T3; SK9452000A3; UA61985C2; AU9539798A; BR9814400A; DE59802477D1; CN1283212A; CZ295730B6; DE19757308A1; JP2001527110A; HK1034529A1; HUP0004654A2

Abstract

The invention relates to a method for producing organopolysiloxane terminated with alkoxy groups, wherein A) organopolysiloxane terminated with HO is reacted with B) alkoxysilane having at least three alkoxy groups and/or whose partial hydrolysate is made to react in the presence of C) acid phosphoric acid ester of general formula (I): (HO)aOP(-O-[(CR12)b-O]c[(CR22)d]e-L-M)(3-a), wherein a = 1 or 2; R?1 and R2¿ = a hydrogen, methyl or hydroxyl radical; b and d = 2 or 3; c = integral values from 2 to 15; e = 0 or 1; L = a radical from the group -O-, -COO-, -OOC-, -CONR?3-, -NR4¿CO- and -CO-; R?3 and R4¿ = a hydrogen or a C¿1?-C10-alkyl radical and M = a monovalent, optionally a hydroxyl, fluorine, chlorine, bromine, C1-C10-alkoxylalkyl or cyano group substituted C1- to C20-hydrocarbon radical, provided that the radicals R?1 and R2¿ can only be at one given time a hydroxyl radical in each hydrocarbon atom. The invention further relates to RTV-1-alkoxy masses comprising the reaction product containing organopolysiloxane terminated with alkoxy groups as the essential constituent.

Description

Crosslinkable with the elimination of alcohols to give elastomers

Organopolysiloxane compositions

The invention relates to the production of organopolysiloxane terminated with alkoxy groups and the use of this organopolysiloxane as a component of RTV-1-alkoxyτnassen.

In the context of the present invention, the term organopolysiloxanes is intended to encompass dimeric, oligomeric and polymeric siloxanes.

Organopolysiloxane compositions which can be stored in the absence of moisture and which crosslink in the presence of moisture at room temperature with the elimination of alcohols, so-called RTV-1 alkoxy compositions, have long been known. They consist essentially of organopolysiloxane terminated with organyloxy groups and, as further constituents, crosslinking agents with at least three hydrolyzable groups, catalyst and optionally additives. The advantage of these RTV-1 alkoxy systems is that they release odorless, neutral, environmentally compatible alcohols as cleavage products during the crosslinking process.

Organopolysiloxane terminated with alkoxy groups is prepared by reacting HO-terminated organopolysiloxane with alkoxysilanes. This is described, for example, in US-A-4,942,211. A disadvantage of this process is that the reaction takes a few hours at room temperature. At elevated temperature, the reaction time is shortened, but it is still long enough to wait until RTV-1 alkoxy compositions can be prepared with the organopolysiloxane terminated with alkoxy groups and other constituents.

It is known to accelerate the reactions of HO-terminated organopolysiloxane with alkoxysilanes using various catalysts. For example, in EP-A-763 557 the reaction in the presence of acidic dialkyl phosphoric acid esters carried out. After the reaction, the dialkylphosphoric acid esters must be deactivated by bases, since otherwise the organopolysiloxanes terminated with alkoxy groups are depolymerized and their crosslinking ability is lost.

The object of the invention is to produce organopolysiloxane terminated with alkoxy groups for RTV-1 alkoxy compositions in the simplest possible way.

The invention relates to a process for the preparation of organopolysiloxane terminated with alkoxy groups, in which

(A) HO-terminated organopolysiloxane with

(B) alkoxysilane which has at least three alkoxy groups and / or its partial hydrolyzates, in the presence of

(C) acidic phosphoric acid ester of the general formula (I)

(HO) _a OP (-0 - [(CR ¹ ₂ ) _b -0] _c [(CR ² ₂ ) _d ] _e -LM) ₍₃ _ _a) (I),

is implemented in which a is the value 1 or 2,

R1 and 2 represent a hydrogen, methyl or hydroxyl radical, b and d the values 2 or 3, c integer values from 2 to 15, e the values 0 or 1

L is a radical from the group -O-, -COO-, -OOC-, -CONR ³ -, -NR ⁴ CO- and -CO-,

R and a hydrogen or and a monovalent, optionally with hydroxyl, fluorine, chlorine, bromine, or cyano groups substituted C ^ - to C2o ^_Ko hl ^{en asserst} ° ffrest, with the proviso that the radicals R 1 and R2 can only be a hydroxyl radical on each carbon atom once.

The process takes place selectively at room temperature with an extremely high reaction rate, so that the components formed immediately after the components (A), (B) and (C) are mixed Organopolysiloxane terminated by alkoxy groups, if appropriate after admixing further constituents, can be used as RTV-1-alkoxyτnasse. It is not necessary to check whether the implementation has been completed.

Another advantage of this process is that there are no side reactions and, for example, the formation of T and Q units has not been observed on linear organopolysiloxane.

The acidic phosphoric acid esters (C) do not have to be deactivated immediately after the reaction.

C preferably denotes integer values from 2 to 10, in particular 2, 3, 4 or 5.

L is preferably a radical -0-. Preferably M represents an optionally with C- _j _-C ₁₀ alkoxyalkyl substituted C _j _- to _C2o hydrocarbon radical, especially an unsubstituted C ₅ to C ₁₈ hydrocarbon radical. V Voorrzzuuggsswweeiissee bbeeddeeuutteenn RR 1 and R2 a hydrogen residue Preferably b and d denote the values 2.

Linear α, co-dihydroxypoly (diorganosiloxanes) of the general formula (II) are preferably used as HO-terminated organopolysiloxane (A)

HO- [R ₂ SiO] _m -H (II),

used where

R monovalent, optionally with fluorine, chlorine, bromine

C ₁ -C ₄ alkoxyalkyl or cyano groups substituted

C- _| _-Cg-hydrocarbon residues means and m means values which correspond to a viscosity of the HO-terminated organopolysiloxane (A) of 0.05 to 1000 Pa.s. Examples of hydrocarbon radicals R are linear and cyclic saturated and unsaturated alkyl radicals such as the methyl radical, aryl radicals such as the phenyl radical, alkaryl radicals such as tolyl radicals and aralkyl radicals such as the benzyl radical.

Unsubstituted hydrocarbon radicals having 1 to 6 carbon atoms are preferred as radical R, the methyl radical being particularly preferred.

The organopolysiloxanes (A) preferably have a viscosity of 100 to 700,000 mPa.s, in particular of 20,000 to 350,000 mPa.s, each measured at 23 ° C.

The alkoxysilanes (B) preferably have the general formula (III)

R ⁵ Si (OR ⁶ ) ₄ (III),

on what

5 and R6 monovalent, optionally with fluorine, chlorine,

Bromo, C ₁ -C ₄ -alkoxyalkyl- or cyano-substituted C- _j _-C ₁₃ hydrocarbon radicals and μ is 0 or 1.

The partial hydrolysates of alkoxysilane (B) are formed by hydrolysis and condensation of in particular 2 to 4 alkoxysilanes. Partial hydrolyzates (B) are, for example, hexamethoxy disiloxane and hexaethoxydisiloxane.

R and preferably each represent unsubstituted

C- _{j ^} -Cg hydrocarbon radicals, especially methyl, ethyl and propyl radicals.

The acidic phosphoric acid esters (C) of the general formula (I) stabilize the RTV-1 alkoxy compositions prepared from the alkoxy group-terminated organopolysiloxane during storage. In particular, the skin formation times remain RTV-1 alkoxy masses are almost constantly stable and discoloration is prevented.

In the general formulas (I) to (III), all R, R ¹ bbiiss RR ssoowwiiee aallllee IInnddiizzeess aa ,, bb ,, cc ,, dd, e, m and μ are independently the same or different.

The tetravalence of the silicon atom applies in all formulas. For example, n + o is at most 4.

The acidic phosphoric acid esters (C) are added based on 500 parts by weight of the HO-terminated organopolysiloxanes (A) to 0.1 to 50 parts by weight, in particular 2 to 20 parts by weight.

The alkoxysilanes (B) are preferably added to the HO-terminated organopolysiloxanes (A) in an excess in terms of the stoichiometric ratios. In order to allow the reaction of the HO-terminated organopolysiloxanes (A) with alkoxysilanes (B) to proceed as completely as possible, 10 to 60 parts by weight, in particular 20 to 50 parts by weight of the alkoxysilanes (B) per 500 parts by weight of the HO-terminated organopolysiloxanes (A ) are used. The unreacted during the reaction ^excess' of alkoxysilanes (B) is in the terminated organopolysiloxane with organyloxy groups and the RTV-1-alkoxy not detrimental and can therefore remain in the reaction product. An excess of alkoxysilanes (B) acts as a crosslinking component in the RTV-1 alkoxy compositions.

The reaction is preferably carried out at temperatures from +20 to ₊ 50 ° C, especially at room temperature. The reaction time is 1 to 10 minutes, depending on the alkoxysilanes (B) used.

The reaction rate during the reaction depends on the one hand on the reactivity of the alkoxysilane (B) used and on the other hand on the acidic phosphoric acid ester (C). The particularly preferred reaction time at room temperature is 2-5 min, which is particularly advantageous for the production of RTV-1 compositions in a one-pot process.

The invention also relates to RTV-1 alkoxy compositions which comprise the reaction product prepared by the above process and containing organopolysiloxane terminated with alkoxy groups as an essential component.

In addition to the above components, the

RTV-1 alkoxy compositions contain other components known per se.

Other substances which can preferably be used in the preparation of the RTV-1 alkoxy compositions are

Bis (trialkoxysilyl) C ₁ -C ₁₂ alkanes in which the alkoxy residues ddiiee BBeeddeeuuttuunnggeenn vvoonn OORR have, for example bis (triethoxysilyl) ethane.

Likewise, condensation catalysts, reinforcing fillers, non-reinforcing fillers, pigments, soluble dyes, fragrances, plasticizers, such as dimethylpolysiloxanes or phosphoric acid esters which are endblocked at room temperature by trimethylsiloxy groups, fungicides, resinous organopolysiloxanes, including fungicides, can be used in the preparation of the RTV-1 alkoxy compositions such from (CH ₃ ) ₃ SiO- _{j / 2} - and Si0 _{4 2} - units, purely organic resins, such as homo- or copolymers of acrylonitrile, styrene, vinyl chloride or propylene, such purely organic resins, in particular copolymers corrosion inhibitors, polyglycols which are esterified and / or etherified can be produced from styrene and n-butyl acrylate, in the presence of diorganopolysiloxane each having an Si-bonded hydroxyl group in the terminal units, by polymerization of the monomers mentioned by means of free radicals can be oxidate ion inhibitors, heat stabilizers, solvents, agents for influencing the electrical properties, such as conductive carbon black, flame retardants, light stabilizers and Agents for prolonging the skin formation time, such as silanes with SiC-bound mercaptoalkyl residues, as well as cell-generating agents, for example azodicarbonamide. Likewise, adhesion promoters, preferably amino-alkyl-functional silanes such as γ-aminopropyltriethoxysilane, can be added.

Condensation catalysts are preferably used. According to the invention, the RTV-1 alkoxy compositions can contain any condensation catalysts which have hitherto been available in compositions which can be stored in the absence of water and which crosslink to form elastomers when water is added at room temperature.

Examples of such condensation catalysts are organic compounds of tin, zinc, zirconium, titanium and aluminum. Preferred among these condensation catalysts are butyl titanates and organic tin compounds, such as di-n-butyltin diacetate, di-n-butyltin dilaurate and reaction products of at least two monovalent hydrocarbon radicals which are bonded via silicon to oxygen and are optionally substituted by an alkoxy group and have hydrolyzable groups as hydrolyzable groups or its oligomer with diorganotin diacy- lat, where in these reaction products all valences of

Tin atoms are saturated by oxygen atoms of the ≡SiOSn≡ group or by SnC-bonded, monovalent organic radicals.

The RTV-1 alkoxy compositions preferably contain fillers. Examples of fillers are non-reinforcing fillers, ie fillers with a BET surface area of up to 50 m / g, such as quartz, diatomaceous earth, calcium silicate, zirconium silicate, zeolite, metal oxide powder, such as aluminum, titanium, iron or zinc oxides or their mixed oxides, barium sulfate, calcium carbonate, gypsum, silicon nitride, silicon carbide, boron nitride, glass and plastic powder, such as polyacrylonitrile powder; reinforcing fillers, i.e. fillers with a BET surface area of more than 50 m / g, such as pyrogenically prepared silica, precipitated Silicic acid, carbon black, such as furnace black and acetylene black and silicon-aluminum mixed oxides with a large BET surface; fibrous fillers such as asbestos and plastic fibers.

The fillers mentioned can be hydrophobicized, for example by treatment with organosilanes or organosiloxanes or with stearic acid or by etherification of hydroxyl groups to alkoxy groups. It can be a type of filler, a mixture of at least two fillers can also be used.

If only reinforcing silica is used as a filler, transparent RTV-1 alkoxy compositions can be produced.

The usual water content of the air is sufficient for the crosslinking of the RTV-1 alkoxy masses. If desired, the crosslinking can also be carried out at temperatures higher or lower than room temperature, e.g. at -5 ° to 10 ° C or at 30 ° to 50 ° C.

The RTV-1 alkoxy compositions according to the invention are thus extremely suitable, for example, as sealing compounds for joints, including vertically extending joints, and similar empty spaces, e.g. 10 to 40 mm clear width, e.g. of buildings, land, water and aircraft, or as adhesives or cementing compounds, e.g. in window construction or in the manufacture of showcases, as well as e.g. for the production of protective coatings or rubber-elastic molded articles and for the insulation of electrical or electronic devices.

In the examples described below, all parts with percentages are by weight unless otherwise stated. Furthermore, all viscosity data relate to a temperature of 25 ° C. Unless otherwise stated, the following examples are given at a pressure of the surrounding atmosphere, that is at about 1000 hPa, and a room temperature, that is at about 20 ° C. at one Temperature that occurs when the reactants are combined at room temperature without additional heating or cooling.

5 examples

example 1

In a planetary mixer with vacuum equipment, 500 g of a dimethylpolysiloxane, which in the terminal units each has a hydroxyl group with a viscosity of 80,000 mPa.s at 23 ° C. with 350 g of a poly-dimethylsiloxane with trimethylsiloxy groups in the terminal units of a viscosity, with the exclusion of water of 100 m ² / s (23 ° C.) and 10 g 5 mixture of alkoxylated phosphoric acid esters of the formulas (OH) ₁ PO [(OCH ₂ CH ₂ ) ₃ _ ₄ -0- (CH ₂ ) ₁₁ _ ₁₄ -CH ₃ ] and (OH) ₂ PO [(OCH ₂ CH ₂ ) ₃ _ ₄ -0- (CH ₂ ) n-i4- ^CH 3] i mixed. Immediately afterwards, the mixture is added in a 25 g methyltrimethoxysilane and homogenized in vacuo for 5 minutes. Thereafter, 0 is added while maintaining the mixing technique customary for RTV-1 compositions in the order given:

13.5 g of γ-aminopropyltriethoxysilane,

80.0 g of pyrogenic, hydrophilic silica with a surface ²⁵ of 150 m ² / g according to BET and

5.0 g of a reaction product which is obtained by heating a mixture of 4 parts of tetraethyl silicate and 2.2 parts of di-n-butyltin diacetate at 120 ° C. for 6 hours at the pressure of the surrounding atmosphere with stirring and at the same time distilling off

^• 3 Λ of the resulting ethyl acetate was produced.

After homogenization in a vacuum, the compound is filled into moisture-tight containers. After various periods of time, samples are taken and the skin formation times (at ³⁵ 23 ° C./50% relative atmospheric humidity) of the elastomers produced therefrom are determined. The results obtained are shown in Table 1. The following mechanical properties of the elastomers were determined:

Shore A: 10; Tensile strength: 1.0 N / m; Elongation at break: 560 ^; Tear resistance: 2.7 N / mm;

Tension value at 100% elongation: 0.2 N / mm

Example 2

Anologic example 1 is used. The following ingredients are added to 600 g of α, ω-dihydroxypolydimethylsiloxane from Example 1 in the order given:

280.0 g polydimethylsiloxane with -Si (CH ₃ ) _{3 end} groups 10.0 g alkoxylated phosphoric acid ester from Example 1 25.0 g vinyltrimethoxysilane,

15.0 g of γ-aminopropyltriethoxysilane,

70.0 g of pyrogenic, hydrophilic silica with a surface area of 150 m ² / g according to BET and 5.0 g of the reaction product of tetraethyl silicate and di-n-butyltin diacetate from Example 1.

The skin formation times of the elastomers produced therefrom are listed in Table 1.

Example 3

Anologic example 1 is used. The following ingredients are added to 500 g of α, ω-dihydroxypolydimethylsiloxane in the order given:

380.0 g polydimethylsiloxane with -Si (CH ₃ ) _{3 end} groups 10.0 g alkoxylated phosphoric acid esters from Example 1 25.0 g methyltrimethoxysilane,

10.0 g of 3- (2-aminoethylamino) propyltrimethoxysilane, 70.0 g of pyrogenic, hydrophilic silica with a surface area of 150 m ² / g according to BET and 4.0 g of the reaction product of tetraethyl silicate and di-n-butyltin diacetate from Example 1.

Example 4

The procedure is analogous to Example 1. The following are mixed: 500.0 g of α, ω-dihydroxypolydimethylsiloxane from Example 1 380.0 g of polydimethylsiloxane with -Si (CH ₃ ) _{3 end} groups 10.0 g of alkoxylated phosphoric acid esters from Example 1 25.0 g of methyltrimethoxysilane,

8.0 g of γ-aminopropyltriethoxysilane, 70.0 g of pyrogenic, hydrophilic silica with a surface area of 150 m ² / g according to BET and 4.0 g of the reaction product of tetraethyl silicate and di-n-butyltin diacetate from Example 1.

Example 5

Anologic example 1 is used. The following are mixed:

500.0 g of α, ω-dihydroxypolydimethylsiloxane from Example 1 380.0 g of polydimethylsiloxane with -Si (CH ₃ ) _{3 end} groups 10.0 g of alkoxylated phosphoric acid ester from Example 1 25.0 g of vinyltrimethoxysilane,

25.0 g of amino-functional siloxane: equilibration product composed of aminopropyltriethoxysilane and a condensate / hydrolyzate of methyltriethoxysilane with an amine number of 2.2, 70.0 g of pyrogenic, hydrophilic silica with a surface area of 150 m ² / g according to BET and 5.0 g of the reaction product of tetraethyl silicate and di-n-butyltin diacetate from Example 1. The skin formation times of the elastomers produced therefrom are listed in Table 1.

Table 1

Example 6:

In a planetary mixer with vacuum equipment, 600g of a polydimethylsiloxane are excluded with water, each having a hydroxyl group in the terminal units and with a viscosity of 80,000 mPa.s at 23 ° C, 300g of a polydimethylsiloxane with trimethylsiloxy groups as terminal units and with a viscosity of 100 mm / s homogeneously mixed at 23 ° C. and 10 g of the alkoxylated phosphoric acid ester from Example 1.

Immediately afterwards, 35 g of methyltrimethoxysilane are added and the mixture is homogenized again for 5 minutes. Then the following ingredients are added in succession to this premixing while maintaining the mixing technique customary for RTV-1 compositions:

15.0 g of γ-aminopropyltriethoxysilane,

70.0 g of pyrogenic, hydrophilic silica with a specific surface of 150 m / g according to BET and 5.0 g of the reaction product of tetraethyl silicate and di-n-butyltin diacetate from Example 1.

After homogenization under reduced pressure, the compo and is filled in moisture-tight containers. After storage for 1 day at room temperature, a skin formation time of 10 minutes (23 ° C / 50% relative air humidity) is determined. After additional 7 days of storage at 50 ° C, a skin formation time of 15 minutes results.

Example 7:

Example 6 is repeated. However, the other ingredients are added to the premix of the same composition in a different order:

70.0 g of pyrogenic, hydrophilic silica with a specific surface of 150 m / g according to BET,

15.0 g of γ-aminopropyltriethoxysilane and 5.0 g of the reaction product of tetraethyl silicate and di-n-butyltin diacetate from Example 1.

After homogenization under reduced pressure, the compo and is filled in moisture-tight containers. After storage for 1 day at room temperature, a skin formation time of 12 minutes (23 ° C / 50% relative air humidity) is determined. After additional 7 days of storage at 50 ° C, a skin formation time of 15 minutes results.

Example 8:

Example 6 is repeated. The further ingredients are added to the premix of the same composition as follows:

After homogenization under reduced pressure, the compound is left to stand for 3 hours with the exclusion of moisture and then 15 g of γ-aminopropyltriethoxysilane are mixed in. After repeated homogenization under reduced pressure, the compound is filled in moisture-tight containers. After storage for 1 day at room temperature, a skin formation time of 12 minutes (23 ° C / 50% relative air humidity) is determined. After additional 7 days of storage at 50 ° C, a skin formation time of 15 minutes results.

Examples 6 to 8 show that the order of adding the

Adhesion promoter γ-aminopropyltriethoxysilane has a negligible influence on the skin formation time. The immediate neutralization of the alkoxylated phosphoric acid ester by the basic adhesion promoter is therefore not necessary.

Example 9:

In a planetary mixer with vacuum equipment, 550g of a polydimethylsiloxane with terminal hydroxyl groups and a viscosity of 80,000 mPa.s at 23 ° C., 325g of a polydimethylsiloxane with terminal trimethylsiloxy groups, 50g methyltrimethoxysilane and 10g of the alkoxylated phosphoric acid ester from Example 1 are mixed homogeneously with exclusion of water. After approx. 10 minutes, the following ingredients are added and these are mixed homogeneously into the total mass:

15.0 g of γ-aminopropyltriethoxysilane,

73.0 g of pyrogenic, hygrophilic silica with a surface area of 150 m ² / g according to BET,

5.0 g of the reaction product of tetraethyl silicate and di-n-butyltin diacetate from Example 1 and 200.0 g of ground, stearic acid-treated chalk. After storage for 1 day at room temperature, a skin formation time of 15 minutes is determined.

After an additional 7 days' storage at 50 ° C, a skin formation time of 20 minutes was determined.

Example 10:

Example 9 was repeated, but with the modification that the same amount of ground, untreated chalk was used instead of the ground, stearic acid-treated chalk.

After 1 day of storage at room temperature, a skin formation time of 20 minutes was determined, after an additional 7 day storage at 50 ° C., a skin formation time of 25 minutes was determined.

Example 11:

Example 9 was repeated, but with the modification that instead of 73 g of pyrogenic, hydrophilic silica with a surface area of 150 m / g according to BET, only 50 g were mixed in and that instead of 200 g of ground, stearic acid-treated chalk the same amount of precipitated, stearic acid-treated chalk was included a surface of 19m / g was used. After 1 day of storage at room temperature, a skin formation time of 15 minutes was determined; after an additional 7 day storage at 50 ° C., the skin formation time was 25 minutes.

Example 12

The procedure is analogous to Example 1. Mix in the following order:

95.3 g of α, ω-dihydroxypolydimethylsiloxane from Example 1 1.2 g of alkoxylated phosphoric acid ester from Example 1 and 3.5 g of methyltrimethoxysilane.

The viscosities of the mixture were measured: The viscosities of the mixture were measured: after 1 h 64000 mPas after 2 h 62400 mPas after 3 h 60800 mPas

Example 13 (comparison example)

The procedure is analogous to Example 1. The following are mixed in the following order: 95.3 g of α, ω-dihydroxypolydimethylsiloxane from Example 1, 1.2 g of di-2-ethylhexyl phosphate (according to EP-A-763 557) and 3.5 g of methyltrimethoxysilane,

The viscosities of the mixture were measured: after 1 h 32000 mPas after 2 h 12000 mPas after 3 h 2000 mPas

Di-2-ethylhexyl phosphate depolymerizes the alkoxy-terminated organopolysiloxane.

Claims

claims

1. A process for the preparation of organopolysiloxane terminated with organyloxy groups, in which

(A) HO-terminated organopolysiloxane with

(C) acidic phosphoric acid ester of the general formula (I)

(HO) _a OP (-O - [(CR ¹ ₂ ) _b -0] _c [(CR ² ₂ ) _d ] _e -LM) ₍₃ _ _a) (I),

is implemented in which a is the value 1 or 2,

1 and 2 represent a hydrogen, methyl or hydroxyl radical, b and d the values 2 or 3, c integer values from 2 to 15, e the values 0 or 1

L is a radical from the group -0-, -COO-, -OOC-, -CONR ³ -, -NR ⁴ CO- and -CO-,

3 and_-, "R4 is a hydrogen or and

M is a monovalent, optionally with hydroxyl, fluorine, chlorine, bromine, or cyano groups are substituted C 1 -C ₂₀ -hydrocarbon radicals, with the proviso that the radicals R 1 and 2 on each carbon atom can only be a hydroxyl radical once.

2. The method according to claim 1, in which as the HO-terminated organopolysiloxane (A) linear α, ω-dihydroxypoly (diorgano) siloxanes of the general formula (II)

HO- [R ₂ SiO] _m -H (II),

are used, in which R is monovalent, optionally substituted by fluorine, chlorine, bromine, C ₄ -C ₄ alkoxyalkyl or cyano groups, and C -Cg hydrocarbon radicals m means values which correspond to a viscosity of the HO-terminated organopolysiloxane (A) of 0.05 to 1000 Pa.s.

3. The method according to claim 1 or 2, wherein the alkoxysilanes (B) the general formula (III)

R ⁵ _μ Si (OR ⁶ ) ₄ _ _μ (III),

have wherein

R and R monovalent, optionally with fluorine, chlorine,

Bromine, C- _| _-C ₄ -alkoxyalkyl or cyano groups substituted C- _] _-C ₁₃ -hydrocarbon radicals and μ mean the values 0 or 1.

RTV-1 alkoxy compositions which comprise the reaction product obtainable according to one of Claims 1 to 3, which contains organopolysiloxane terminated with alkoxy groups as an essential constituent.